Method for discharging fluid

ABSTRACT

In conventional fluid discharge devices, a discharge head used should be increased in size according to increase in size of a workpiece such as silicon wafer. However, if the discharge head increases in length, a deformation amount of a mask used for discharging the fluid on the workpiece increases, thereby the discharging amount varies. Discharging the fluid in a reciprocating manner is performed using a fluid discharging device including a head unit having a width shorter than a length of the workpiece. A suction port having opening portions each having a slit shape are disposed on the both sides of the discharge nozzle in a vicinity of the discharge nozzle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/063,155 filed Jun. 15, 2018 (now U.S. Pat. No. ______, issued______), which is a U.S. National Phase Application under 35 U.S.C. 371of International Application No. PCT/JP2016/087369 filed on Dec. 15,2016 and published in Japanese as WO 2017/104745 A1 on Jun. 22, 2017,which is based on and claims the benefit of priority from JapanesePatent Application No. 2016-165458, filed Aug. 26, 2016 and JapanesePatent Application Nos. 2015-244139 and 2015-244141, both filed onDec.15, 2015. The entire disclosures of all of the above applicationsare incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a device which discharges fluid such asmolten solder or an adhesive agent on a substrate or a workpiece of anelectronic component such as a semiconductor.

BACKGROUND ART

To mount an electronic component, such as a semiconductor, on a printedcircuit board of electronic equipment or to assemble an electroniccomponent, such as a semiconductor, solder or an adhesive agent is used.Particularly, soldering cannot be performed on an electronic componentmade of ceramic or the like without performing any treatment. In view ofthe above, pads formed of a plating film are formed on a surface of anelectronic component workpiece, and solder bumps (humps) are formed onthe pads. Thereafter, soldering is performed using the bumps.

Conventionally, a method which uses a solder paste is used as a methodfor forming solder bumps in many cases. A solder paste is applied on aplating film of a workpiece by a printer or a dispenser and, thereafter,the solder paste is subjected to reflow heating so as to melt the solderpaste to form bumps. This method enables low cost. However, there is alower limit to applying a solder paste by printing and hence, bumpswhich correspond to a fine circuit pattern cannot be formed.

There is also a method for forming a bump by making use of a solderball. Fine solder balls are mounted on an electronic componentworkpiece, and the solder balls are subjected to reflow heating, thusforming bumps. With the use of such a method, bumps which correspond toa fine circuit pattern can be formed. However, cost for solder balls perse is high so that cost increases as a whole.

As a method for forming bumps which can manage a fine circuit pattern atlow cost, a so-called molten solder method has been attracting attentionwhere molten solder is discharged so as to form solder bumps. Forexample, a solder deposition device disclosed in PTL 1 described belowis known as a device for realizing the molten solder method. In thissolder deposition device, a nozzle opening portion of a vessel whichstores molten solder is caused to scan in the horizontal direction, thusefficiently suppling molten solder to a plurality of portions. A bumpforming device is also known which includes a mechanism for lifting anozzle head from a mask after the operation is finished and the nozzlehead is cooled (for example, PTL 2 described below).

CITATION LIST Patent Literature

PTL 1: Japanese Patent Application Laid-Open No. H2-015698

PTL 2: WO2013/058299A

SUMMARY OF INVENTION Technical Problem

In a solder bump forming device which makes use of molten solder or in afluid discharge device such as an adhesive agent application device, ingeneral, as shown in FIG. 1, the size of a discharge head is equal tothe size of a workpiece such as a silicon wafer or a printed circuitboard. The discharge head moves in a fixed direction. With such aconfiguration, it is possible to prevent a deflection of a mask which iscaused by moving a squeegee while the number of scanning operations issmall.

When a silicon wafer, a printed circuit board or the like has a smallsize, such a device causes no problems. However, when such a device isused for a workpiece of a large size such as a silicon wafer of 300 mm,it is necessary to increase the length of the discharge head tocorrespond to the size of the workpiece. When the length of thedischarge head increases, a pressure applied to the workpiece from thedischarge head is not always uniformly distributed, and the pressurevaries. Accordingly, a mask is deformed due to deflection generated by astroke and hence, a uniform amount of fluid cannot be discharged fromthe discharge head. Further, assuming that fluid is discharged using asmall head a plurality of times, when a discharge pattern is a finepattern, the distance between adjacent discharge portions is small andhence, the fluid is discharged in an overlapping manner. For thisreason, the amount of discharge is unstable.

In view of the above, there has been a demand for provision of a fluidapplication device which can apply fluid at a stable amount of dischargeeven when fluid is discharged to a workpiece of a large size such as asilicon wafer of 300 mm. Further, it is desirable that fluid can beapplied to a region of a workpiece as widely as possible.

Solution to Problem

The present invention has been made to overcome at least a portion ofthe above-mentioned problem, and can be realized as the followingaspects, for example.

According to a first aspect of the present invention, there is provideda method for discharging fluid for applying the fluid into a mask on anelectronic component workpiece. The method uses a fluid discharge deviceincluding a head unit which includes: a tank capable of storing thefluid; and a discharge head. The head unit has a width shorter than alength of the workpiece. The discharge head has a suction port formedfor sucking a substance in the mask on the workpiece, and a dischargenozzle formed in a vicinity of the suction port for discharging thefluid. The suction port is provided on a forward side of the dischargehead in a traveling direction. The fluid is discharged using the fluiddischarge device such that the discharge head reciprocates with respectto the workpiece.

According to the first aspect, the discharge head is reciprocated withrespect to a workpiece as shown in FIG. 2 and hence, the deformation ofthe mask can be reduced. To be more specific, the deformation of themask is generated when the discharge head moves in the first direction.However, the discharge head is moved again in the second direction whichis the direction opposite to the first direction and hence, the maskwhich is deformed once returns to an original state. Accordingly, thedeformation of the mask can be reduced.

According to a second aspect of the present invention, there is provideda fluid discharge device for applying fluid into a mask on an electroniccomponent workpiece. The fluid discharge device includes a head unitwhich includes a tank capable of storing the fluid, and a dischargehead. The head unit has a width shorter than a length of the workpiece.The discharge head has a suction port formed in a vicinity of adischarge nozzle for discharging the fluid, and having an openingportion having a slit shape for sucking a substance in the mask on theworkpiece. The suction port is disposed on both sides of the dischargenozzle.

According to the second aspect, the fluid is discharged whilereciprocating the discharge head and hence, the deformation of the maskis not biased in one direction so that the deformation of the mask isreduced. Accordingly, the amount of discharge does not vary and hence,the fluid of a stable amount of discharge can be discharged. Therefore,it is possible to eliminate a large amount of correction which isconventionally required on applying the fluid into a fine mask for aworkpiece and hence, productivity can be remarkably enhanced.

According to a third aspect of the present invention, there is provideda fluid discharge device for applying fluid into a mask on an electroniccomponent workpiece. The fluid discharge device includes a plurality ofhead units each of which includes a tank capable of storing the fluidand a discharge head. Each head unit has a smaller size than theworkpiece. The head units move in a horizontal direction above theworkpiece in synchronism with each other. Each discharge head has asuction port formed for sucking a substance in the mask on theworkpiece, and a discharge nozzle formed in a vicinity of the suctionport for discharging the fluid. The suction port is provided on aforward side of the discharge head in a traveling direction. The suctionport degasses and decompresses air in the mask on the workpiece beforethe fluid is discharged, so that a uniform amount of fluid can be stablydischarged.

According to a fourth aspect of the present invention, there is provideda method for discharging fluid for applying the fluid into a mask on anelectronic component workpiece. The method for discharging the fluidincludes a plurality of head units each of which includes a tank capableof storing the fluid and a discharge head. Each head unit has a smallersize than the workpiece, and an angle of each head unit is changeable.The head units move in a horizontal direction above the workpiece insynchronism with each other. Each discharge head has a suction portformed for sucking a substance in the mask on the workpiece, and adischarge nozzle formed in a vicinity of the suction port fordischarging the fluid. The suction port is provided on a forward side ofthe discharge head in a traveling direction. The suction port degassesand decompresses air in the mask on the workpiece before the fluid isdischarged, so that a uniform amount of fluid can be stably discharged.

Split head units may have a size which allows a pressure in the verticaldirection applied by the head units to be uniform. To be more specific,it is preferable that the size of each head unit be set to ½ to ¼ of thelateral length of a workpiece. Further, the number of the plurality ofhead units used in this application may be determined corresponding tothe size of a workpiece. The number of head units is appropriately setto 2 to 4 in view of ease of handling. When the fluid is discharged to aworkpiece having a circular shape such as a silicon wafer, it is optimalto use three head units. As in the case shown in FIG. 6, in thedischarge of the fluid to a workpiece having a circular shape, the headunits are horizontally moved in a forward and rearward direction, andangles of the head units disposed on the left and right sides arechanged along a circumference of the workpiece. With such aconfiguration, even when a workpiece has a circular shape where thedischarge of the fluid is difficult compared to a rectangular shape, auniform amount of discharge can be acquired.

According to the fourth aspect, the head unit has a shorter length thanthe workpiece. Accordingly, there is no possibility that a pressure tobe applied to a workpiece from the discharge heads is not alwaysuniformly distributed so that an amount of discharge varies. Therefore,a uniform pressure can be applied to the workpiece. Further, the headunits move in the horizontal direction above the workpiece insynchronism with each other and hence, there is no discharge leakagewhereby the fluid of a stable amount of discharge can be discharged.Accordingly, it is possible to eliminate a large amount of correctionwhich is conventionally required on applying the fluid into a fine maskfor a workpiece and hence, productivity can be remarkably enhanced.

According to a fifth aspect of the present invention, there is provideda fluid discharge device for applying fluid on an electronic componentworkpiece. The fluid discharge device includes: a first stage forsupporting the workpiece; a first discharge head configured to dischargethe fluid while moving in a straight line in a horizontal directionabove the workpiece, and to move from an initial position locatedoutside the first stage to a final position located outside the firststage through an area above the first stage; a second discharge headconfigured to discharge the fluid while changing an arrangement angle ofthe second discharge head and moving in the horizontal direction abovethe first stage; and a second stage disposed, on a movement path of thefirst discharge head, from the initial position to an outer edge of thefirst stage and from an outer edge of the first stage to the finalposition, and disposed such that the discharge head is slidable on thesecond stage. A range in which the fluid can be discharged in each ofthe first discharge head and the second discharge head is smaller than awidth of a region on the first stage where the workpiece is disposed.

According to the fluid discharge device of the fifth aspect, the fluidis discharged using a plurality of discharge heads having a smaller sizethan the workpiece. Accordingly, even when a workpiece having a largesize is processed, a pressure to be applied to the workpiece from thedischarge heads is approximately uniformly distributed. Therefore, theamount of discharge from the discharge heads is stabilized. Further, thesecond movable stage is disposed on the movement path of the firstdischarge head at a position outside the first stage and hence, thefirst discharge head can apply the fluid from an outer edge to anotherouter edge of the workpiece. Further, the second discharge head moveswhile changing the arrangement angle of the second discharge head andhence, even when the application is started from a position on theworkpiece, the fluid can be discharged in a wide range.

According to a sixth aspect of the present invention, in the fifthaspect, the second discharge head includes two discharge heads. The twodischarge heads are respectively disposed on both sides of the firstdischarge head. According to the sixth aspect, the fluid can beefficiently applied to approximately the whole region of the workpiecehaving a circular shape.

According to a seventh aspect of the present invention, in the fifth orsixth aspect, the first discharge head and the second discharge head areconfigured to move simultaneously in synchronism with each other.According to the seventh aspect, a processing time can be shortened.

According to an eighth aspect of the present invention, in any one ofthe fifth to seventh aspects, the first discharge head and the seconddischarge head are configured to cover, in cooperation with each other,a region on the workpiece where the fluid is to be dischargedsubstantially without causing overlapping. According to the eighthaspect, the fluid can be efficiently applied. Further, the fluid is notapplied to the same portion a plurality of times. Accordingly, avariation in application amount can be suppressed.

According to a ninth aspect of the present invention, in any one of thefifth to eighth aspects, the range in which the fluid can be dischargedin each of the first discharge head and the second discharge head is setto ¼ or more and ½ or less of a width of the region on the first stagewhere the workpiece is disposed. According to the ninth aspect, theadvantageous effect of the fifth aspect can be acquired without makingthe configuration of the device excessively complicated.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing a discharge head of a conventionalfluid application device.

FIG. 2 is a schematic view showing a discharge head of a fluidapplication device according to one embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of the fluid applicationdevice according to one embodiment of the present invention.

FIG. 4 is a schematic view showing the discharge head of the fluidapplication device according to one embodiment of the present invention.

FIG. 5 is a detail view showing a configuration of the discharge head ofthe fluid application device according to one embodiment of the presentinvention.

FIG. 6 is a schematic view showing discharge heads of a fluidapplication device according to a second embodiment of the presentinvention.

FIG. 7 is a view showing movement paths of the discharge heads.

FIG. 8 is a view showing the movement paths of the discharge heads.

FIG. 9 is a view showing the movement paths of the discharge heads.

FIG. 10 is a view showing the movement paths of the discharge heads.

FIG. 11 is a view showing the movement paths of the discharge heads.

FIG. 12 is a top plan view showing the arrangement of discharge headsand stages of a fluid application device according to a third embodimentof the present invention.

FIG. 13 is a cross-sectional view showing the arrangement of the stages.

FIG. 14 is a view showing movement paths of the discharge heads.

FIG. 15 is a view showing the movement paths of the discharge heads.

FIG. 16 is a view showing the movement paths of the discharge heads.

DESCRIPTION OF EMBODIMENTS A. First Embodiment

First, a configuration of a head unit 1 of a fluid application device isdescribed. FIG. 3 is a view showing details of the head unit 1 accordingto the present invention. The head unit 1 includes a fluid tank 2 whichcan store molten solder or the like, and a discharge head 3 which isformed on a lower end of the head unit 1. When fluid which requires atemperature control, such as molten solder, is used, a heating means maybe mounted at the fluid tank 2. For example, a heater 4 may be woundaround a side portion of the fluid tank 2. The discharge head 3 has afluid discharge nozzle 5 and suction ports 6 which are formed at a lowerend of the head. The suction ports 6 are formed in the discharge head 3such that a suction step can be performed prior to a step performed bythe fluid discharge nozzle 5 in the traveling direction. When fluidwhich requires a temperature control is used also in the fluid dischargenozzle 5 and the suction ports 6, a heater 4 may also be mounted at alower end of the discharge head 3.

A circular shape, a slit shape or any other known shape may be adoptedas the shape of a nozzle opening of the discharge head 3. Particularly,with the use of a slit shape as the shape of the nozzle opening, thefluid can be discharged to a plurality of discharge targets on aworkpiece 7 simultaneously. A circular shape, a slit shape or any otherknown shape may be adopted also as the shape of the suction port 6formed in the discharge head 3. However, with the use of a slit shape asthe shape of the opening, air or the fluid which has already dischargedin a mask 8 can be simultaneously removed with respect to a plurality ofportions on the workpiece 7 such as a silicon wafer or a printed circuitboard. Further, in the present application, the suction port 6 is formedin front of and behind the discharge head 3 as shown in FIG. 4 so thatthe deformation of the mask can be made uniform. Accordingly, the fluidcan be stably discharged in a reciprocating manner.

Next, the overall configuration is described. As shown in FIG. 3, thefluid application device of the present invention is movable in theupward and downward direction (Y) as a whole such that the fluidapplication device approaches and separates from the electroniccomponent workpiece 7 to which the fluid is to be applied. The fluidapplication device is movable also in the horizontal direction (X). Themask 8 which is made from polyimide or a resist is placed on an upperportion of the workpiece 7. On discharging the fluid, the discharge head3 descends to a position where the fluid discharge nozzle 5 comes intocontact with the workpiece 7. The liquid discharge head 3 moveshorizontally while maintaining a contact state between the fluiddischarge nozzle 5 and the workpiece 7. When the discharge head 3 moveshorizontally, first, air in the mask 8, which is installed on theworkpiece 7, is sucked through the suction port 6 formed in thedischarge head 3 such that a suction step can be performed first in thetraveling direction. The fluid discharged into the mask 8 by a second orlater discharge can be also sucked at this stage of operation. Whenfluid which requires a heating means is used, the fluid is heated by theheater 4 provided at a lower portion of the discharge head 3, thusallowing the fluid to be sucked. Thereafter, when the liquid dischargehead 3 moves horizontally, the fluid is discharged from the opening ofthe fluid discharge nozzle 5 so that the fluid is applied into the mask8 on the workpiece 7. When the application of the fluid is finished, theliquid discharge head 3 is raised so as to separate from the workpiece7. The same step may be performed also in the case where the mask 8 isnot used.

The fluid discharge device 1 includes the heater 4 for maintaining thefluid in the tank 2 at a desired temperature. The heater 4 may beincorporated in a wall portion of the tank 2. The heater 4 is managedand controlled so as to heat to an appropriate temperature formaintaining a viscosity of the fluid 9 in the tank 2, such as moltensolder, which viscosity is optimal for conditions for applying the fluid9.

Although not shown in the drawing, the fluid discharge device 1 isconnected to a pressure supply means 11, which allows fluidcommunication, through an extension pipeline 10 from the tank 2. Thefluid discharge device 1 is connected to a reduced pressure supply means13, which allows fluid communication, through a suction pipe extensionpipeline 12 which continues from the suction port 6. The pressure supplymeans 11 includes a pressure generating source 14 which generates anitrogen gas of a pressure of 0.06 to 0.1 MPa (not limited to such avalue), for example. The pressure generating source 14 supplies apressure into the tank 2 through a gate valve 15 and a three-way valve16. Molten solder held in the tank 2 is injected from the opening of thefluid discharge nozzle 5 by a pressure from the pressure generatingsource 14.

The reduced pressure supply means 13 includes a micro ejector 16 whichis a reduced pressure generating device. The reduced pressure generatingdevice 16 is connected to a pressure generating source 19, whichgenerates a nitrogen gas of a pressure of 0.4 MPa (not limited to such avalue), through a regulator 17 and a throttle valve 18, for example. Thereduced pressure generating device 16 supplies a negative pressure tothe suction port 6 through the suction pipe extension pipeline 12.

The fluid discharge device includes a pressure sensor 20 and acontroller 21. The pressure sensor 20 is connected to the three-wayvalve 18 disposed in the extension pipeline 17 in fluid communicationwith the inside of the tank 2, and the pressure sensor 20 monitors apressure in the tank 2. A signal indicating a pressure in the tank 2 istransmitted to the controller 21 from the pressure sensor 20. Thecontroller 21 operates the pressure generating source 14, the reducedpressure generating device 16, the regulator 17, the pressure generatingsource 19 and the respective valves according to the progress of theoperating steps to supply a pressure into the tank 2. An appropriatevalue of pressure required to be supplied is determined based on asignal from the pressure sensor 20. When molten solder in the tank 2 isinjected from the opening of the fluid discharge nozzle 5, the operationis performed so as to allow fluid communication between the inside ofthe tank 2 and the pressure sensor 20. A magnitude of positive pressureto be supplied into the tank 2 can be varied by adjusting a value ofpressure generated by the pressure generating source 14, for example.Alternatively, a value of pressure may be varied by adjusting, with useof the controller 21, a regulating valve (not shown in the drawing)disposed in the pressure supply means 11.

An appropriate value of pressure, which is required to be supplied intothe tank 2, for causing fluid such as molten solder to be injected fromthe opening of the fluid discharge nozzle 5 or for holding the fluid inthe tank 2 is influenced also by an amount (weight) of molten solderstored in the tank 2. Accordingly, the controller 21 may be configuredto receive data relating to the amount of fluid in the tank 2. In thiscase, the controller 21 can calculate an appropriate value of pressurein the tank for injecting the fluid or for hold the fluid in the tank,from the data on the amount of fluid in the tank 2. Further, thecontroller 21 can compare the appropriate value of pressure in the tankand an actual value of pressure in the tank, which the signal from thepressure sensor 20 indicates, to adjust the pressure generating source14 and the respective valves such that an appropriate pressure in thetank is obtained.

To reduce fluctuations in the above-mentioned appropriate value ofpressure in the tank, which are caused by fluctuations in the amount offluid in the tank 2, as much as possible, the fluid supply device 22 maybe provided such that the fluid supply device 22 is connected to thetank 2. When molten solder in the tank 2 is consumed during theoperation of the fluid discharge device, the fluid supply device 22 canautomatically supply an additional fluid such that the amount of fluidin the tank 2 is always kept approximately constant. Any known methodcan be used so as to acquire the amount of fluid in the tank 2. Theamount of molten solder in the tank 2 can be inferred from the number ofproducts processed or the like. When the above-mentioned appropriatevalue of pressure in the tank which corresponds to the amount of fluidin the tank can be acquired empirically, the controller 21 can control apressure which is to be supplied into the tank 2 only based on a signalfrom the pressure sensor 20.

Finally, the operation of the fluid discharge device of the firstembodiment is described. The discharge head 3 of the first embodiment isfixed at a fixed position separated from the workpiece 7 at a distance.However, on discharging the fluid, the discharge head 3 moves in theupward and downward direction as well as in the horizontal direction sothat the discharge head 3 descends to a position where the dischargehead 3 comes into contact with a discharge portion of the mask 8 on theworkpiece 7. A pressure supplied from the pressure generating source 14is supplied into the tank 2 through the gate valve 15. The fluid 9 heldin the tank 2 is injected from the opening of the discharge nozzle 5 bythe pressure from the pressure generating source 14. The discharge heads3 move such that the discharge heads 3 which are discharging the fluid 9always horizontally move so that the side where the suction nozzle 5 isprovided is located forward, and the discharge nozzle 5 discharges thefluid after a pressure of air in an opening portion of the mask 8 on theworkpiece 7 is reduced. After discharging the fluid in one directioninto the opening portion of the mask 8 on the workpiece 7 is finished,then, the return movement of the discharge head 3 is performed. Withsuch operations, a reciprocating movement of the discharge head 3 iscompleted. According to the above-mentioned operations, the dischargehead 3 discharges the fluid while performing a reciprocating operationwith respect to the workpiece 7. Therefore, the deformation of the maskis not biased in one direction so that the deformation of the mask canbe reduced.

B. Second Embodiment

Hereinafter, a second embodiment of the present invention is describedmainly with respect to points which differ from those of the firstembodiment. The configurations of the second embodiment are equal to thecorresponding configurations of the first embodiment unless otherwisespecified.

The operation of a fluid discharge device of the second embodiment isdescribed. Head units 1 in the second embodiment are fixed at fixedpositions separated from a workpiece 7 at a distance. However, ondischarging the fluid, the head units 1 move in the upward and downwarddirection as well as in the horizontal direction so that the dischargeheads 3 descend to the position where the discharge heads 3 come intocontact with discharge portions of a mask 8 on the workpiece 7. FIG. 7Aillustrates one example showing a state where the plurality of headunits 1 descend on discharging the fluid to a silicon wafer. The fluiddischarge device of the second embodiment includes three head units 1.The center head unit is disposed parallel to the traveling direction.The left and right head units are disposed along a workpiece having acircular shape, thus being disposed non-parallel to the travelingdirection. When the head units 1 descend from an initial position, thehead units 1 are held in a state where the left head unit is rotatedclockwise by 10 to 60 degrees, the center head unit is parallel to theworkpiece, and the right head unit is rotated counterclockwise by 10 to60 degrees. Distal ends of the left and right head units on the centerside of the workpiece are disposed forward, in the traveling direction,of the head unit 1 disposed at the center. When the heads movehorizontally in the traveling direction, the left head unit turnscounterclockwise, and the right head unit turns clockwise so that theleft and right head units approach a state parallel to the travelingdirection.

FIG. 7B illustrates one example showing a state where the three headunits 1 are in the vicinity of a center portion of a silicon wafer. Allof the center, left and right head units 1 are parallel to the travelingdirection. When three head units 1 move past the center portion of thesilicon wafer, the left head unit turns counterclockwise, and the righthead unit turns clockwise. FIG. 8C shows a state where the three headunits 1 reach a final position. When the head units 1 are at the finalposition, the head units 1 are held in a state where the left head unitis rotated counterclockwise by 10 to 60 degrees, the center head unit isparallel to the workpiece, and the right head unit is rotated clockwiseby 10 to 60 degrees. In such a state, in contrast to the initialposition, the center head unit 1 is parallel to the traveling direction,and the left and right head units are disposed along the workpiecehaving a circular shape, thus being non-parallel to the travelingdirection. The distal ends of the left and right head units on thecenter side of the workpiece are disposed forward, in the travelingdirection, of the head unit disposed at the center. FIG. 8D shows astate where the three head units move to positions outside the siliconwafer to remove the mask. In such a position, in the same manner as thestate shown in FIG. 8C, the center head unit is parallel to thetraveling direction, and the left and right head units are disposedalong the workpiece having a circular shape, thus being non-parallel tothe traveling direction. The distal ends of the left and right headunits on the center side of the workpiece are disposed forward, in thetraveling direction, of the head unit disposed at the center. The leftand right head units of the fluid discharge device of the presentinvention can turn above a workpiece toward an outer periphery of theworkpiece by 10 to 60 degrees on moving from the initial position to thefinal position.

The discharge heads 3 moves such that the discharge heads 3 which aredischarging the fluid 9 horizontally move so that the side where thesuction nozzle 5 is provided is located forward, and the dischargenozzle 5 discharges the fluid after a pressure of air in an openingportion of the mask 8 on the workpiece 7 is reduced. A pressure suppliedfrom the pressure generating source 14 is supplied into the tank 2through a gate valve 15. The fluid 9 held in the tank 2 is injected fromthe opening of the discharge nozzle 5 by a pressure from the pressuregenerating source 14. The discharge heads 3 move horizontally whilebeing in contact with an upper surface of the mask 8 on the workpiece 7,and the application of the fluid within a determined range is completed.According to the above-mentioned operations in this embodiment, thefluid is discharged using the plurality of discharge heads 3 having asmaller size than the workpiece 7. Accordingly, it is possible tosuppress variation in the amount of discharge so that the amount ofdischarge can be stabilized.

FIGS. 9 to 11 show specific example of movement paths of discharge heads3 a to 3 c. FIG. 9 shows the initial position of the discharge heads 3 ato 3 c before scanning is performed. The first discharge head 3 a isdisposed outside the workpiece 7. The longitudinal direction of thefirst discharge head 3 a is perpendicular to the traveling direction ofthe first discharge head 3 a (the direction toward the upper side of thepaper). The second discharge heads 3 b, 3 c are disposed so as to be incontact with an inner periphery of the workpiece 7 having a circularshape. In other words, the second discharge heads 3 b, 3 c are disposedforward of the first discharge head 3 a in the traveling direction. Thelongitudinal directions of the second discharge heads 3 b, 3 c areinclined with respect to the traveling direction of the discharge heads3 a to 3 c (the direction toward the upper side of the paper). Such aninclination may be set to an angle of 10 to 60 degrees with respect tothe traveling direction, for example. The second discharge head 3 bturns counterclockwise as the second discharge head 3 b travels in thetraveling direction, and the second discharge head 3 c turns clockwiseas the second discharge head 3 c travels in the traveling direction. Theoperation where the second discharge heads 3 b, 3 c travel in thetraveling direction while turning can be realized by a robot arm, forexample.

FIG. 10 shows the discharge heads 3 a to 3 c at the intermediateposition during scanning. The first discharge head 3 a moves in astraight line from the initial position shown in FIG. 9 to the center ofthe workpiece 7. A reference point RPa of the first discharge head 3 amoves along a straight line L1. The second discharge heads 3 b, 3 ctravel in the traveling direction from the initial position shown inFIG. 9 while turning so that the second discharge heads 3 b, 3 c aredisposed at the same arrangement angle as the first discharge head 3 a.That is, the longitudinal direction of the first discharge head 3 a isparallel to the longitudinal directions of the second discharge heads 3b, 3 c. In this turning movement, reference points RPb, RPc of thesecond discharge heads 3 b, 3 c respectively move along the straightlines L1, L2. The reference points RPb, RPc are set at end portions ofthe discharge nozzles 5 on the first discharge head 3 a side.

FIG. 11 shows the final position of the discharge heads 3 a to 3 c afterthe scanning is finished. The first discharge head 3 a moves to theposition outside the workpiece 7 (the position outside the workpiece 7on the side opposite to the initial position) from the intermediateposition shown in FIG. 10. The second discharge heads 3 b, 3 c travel inthe traveling direction from the intermediate position shown in FIG. 10while turning so that the second discharge heads 3 b, 3 c are inclinedwith respect to the traveling direction of the discharge heads 3 a to 3c (the direction toward the upper side of the paper). The direction ofthis inclination is opposite to the direction of the inclination at theinitial position. This inclination may be set to an angle of 10 to 60degrees with respect to the traveling direction, for example.

The discharge heads 3 a to 3 c move as described above so that the fluid9 can be applied to approximately the whole region of the workpiece 7.To be more specific, the application of the fluid 9 for a center regionA1 is covered by the first discharge head 3 a. The application of thefluid 9 for a left region A2 is covered by the second discharge head 3 bon the left side. The application of the fluid 9 for a right region A3is covered by the second discharge head 3 c on the right side. Byadjusting regions where the discharge nozzles 5 a to 5 c of thedischarge heads 3 a to 3 c are formed and the reference positions RP1 toRP3, it is possible to cover a region on the workpiece 7 where the fluidis to be discharged substantially without causing the overlapping.

C. Third Embodiment

Hereinafter, a third embodiment of the present invention is described.FIG. 3 is a schematic view showing a schematic configuration of a solderbump forming device which is one example of a fluid application deviceaccording to a third embodiment. The solder bump forming device is adevice which applies fluid 9 (molten solder in this embodiment) on anelectronic component workpiece 7 (for example, a silicon wafer, aprinted circuit board or the like) to form solder bumps. As shown inFIG. 3, the solder bump forming device includes a discharge head unit 1,a pressure supply means 11, a pressure generating source 14, a microejector 16, a pressure generating source 19, and a fluid supply device22. The solder bump forming device also includes stages 30 to 32 (seeFIG. 12). The details of such configurations are described later.

FIG. 5 is a schematic view showing the discharge head unit 1 of thesolder bump forming device. As shown in FIG. 5, the discharge head unit1 includes a fluid tank 2 which can store the fluid 9, and a dischargehead 3 which is formed on a lower end of the discharge head unit 1. Thedischarge head unit 1 is configured such that the discharge head unit 1can be moved in the horizontal direction above the workpiece 7 by anyactuator (not shown in the drawing). In this embodiment, the dischargehead unit 1 slidingly moves on a mask 8 disposed on the workpiece 7. Themask 8 has a plurality of hole portions formed at portions where solderbumps are to be formed. These hole portions penetrate the mask 8 in thethickness direction of the mask 8 (vertical direction). The mask 8 maybe made from polyimide or a resist, for example. Further, the dischargehead unit 1 is configured such that the discharge head unit 1 can bemoved in the vertical direction, that is, can be moved so as to approachand separate from the workpiece 7.

As shown in FIG. 3, the fluid tank 2 may be connected to the fluidsupply device 22. The fluid supply device 22 can automatically replenishthe fluid 9 when the fluid 9 in the tank 2 is consumed, such that theamount of fluid stored in the fluid tank 2 is always kept approximatelyconstant. With such a configuration, it is possible to suppressfluctuations in pressure in the tank which are caused by fluctuations inthe amount of fluid stored in the fluid tank 2.

In this embodiment, the discharge head unit 1 includes a heater 4 formaintaining the fluid 9 in the tank 2 at a desired temperature. Theheater 4 may be incorporated in a wall portion of the tank 2. The heater4 is controlled so as to heat the fluid 9 to an appropriate temperaturefor maintaining a viscosity of the fluid 9 in the tank 2 which viscosityis optimal for conditions for applying the fluid 9.

As shown in FIG. 5, the discharge head 3 has a discharge nozzle 5 and asuction port 6. The discharge nozzle 5 penetrates the discharge head 3in the vertical direction thus communicating with the fluid tank 2. Asshown in FIG. 3, the fluid tank 2 is connected to the pressure supplymeans 11 through an extension pipeline 10. The pressure supply means 11includes a pressure generating source 14 which generates a nitrogen gasof a pressure of 0.06 to 0.1 MPa (not limited to such a value), forexample. The pressure generating source 14 supplies a pressure to thedischarge head unit 1 through a gate valve and a three-way valve. Withthe supply of such a pressure, the fluid 9 in the tank 2 is dischargedfrom the discharge nozzle 5.

As shown in FIG. 5, the suction port 6 penetrates the discharge head 3in the vertical direction thus communicating with the suction pipeextension pipeline 12. As shown in FIG. 3, the suction pipe extensionpipeline 12 is connected to a reduced pressure supply means 13. Thereduced pressure supply means 13 includes a micro ejector 16 which is areduced pressure generating device. The micro ejector 16 is connected toa pressure generating source 19, which generates a nitrogen gas of apressure of 0.4 MPa (not limited to such a value), through a regulatorand a throttle valve 18, for example. The reduced pressure supply means13 supplies a negative pressure to the suction port 6 through thesuction pipe extension pipeline 12.

The suction port 6 is disposed forward of the discharge nozzle 5 in thetraveling direction of the discharge head unit 1. Accordingly, theinside of the hole portions of the mask 8 can be degassed anddecompressed through the suction port 6 before the fluid is dischargedfrom the discharge nozzle 5. With such a configuration, a uniform amountof fluid can be stably discharged.

A circular shape, a slit shape or any other known shape may be adoptedas the shape of an opening of the discharge nozzle 5. Particularly, whena slit shape is adopted as the shape of the opening of the dischargenozzle 5, the fluid can be discharged into a plurality of hole portionsof the mask 8 simultaneously. A circular shape, a slit shape or anyother known shape may be adopted also as the shape of an opening of thesuction port 6. When a slit shape is adopted as the shape of the openingof the suction port 6, air and the fluid which has already dischargedcan be sucked at a plurality of portions simultaneously.

The operation of the above-mentioned solder bump forming device isschematically described hereinafter. On discharging the fluid, thedischarge head unit 1 descends to a position where the discharge head 3(that is, the opening portion positioned at the lower end of thedischarge nozzle 5) comes into contact with the mask 8. Then, thedischarge head 3 moves in the horizontal direction while maintaining acontact state between the discharge nozzle 5 and the mask 8. When thedischarge head 3 moves horizontally, first, air in the hole portions ofthe mask 8 disposed on the workpiece 7 is sucked through the suctionport 6 formed on the forward side of the discharge head 3 in thetraveling direction. When the discharge head 3 scans above the same holeportion a plurality of times, the fluid 9 previously discharged into thehole portion is also sucked at this stage of operation. A heater may bedisposed at a lower portion of the discharge head 3. With such aconfiguration, the fluid 9 previously discharged into the hole portionis not solidified. Accordingly, the fluid can be reliably sucked.Thereafter, when the discharge head 3 further moves horizontally, thefluid 9 is discharged from the opening of the discharge nozzle 5 intothe hole portions of the mask 8 after the suction operation is performedby the suction port 6. With such operations, the fluid 9 is applied intothe hole portions of the mask 8 on the workpiece 7. When the applicationof the fluid 9 is finished, the discharge head 3 is raised so as toseparate from the mask 8. The same step may be performed also in thecase where the mask 8 is not used.

FIG. 12 is a top plan view showing the arrangement of the discharge headunits 1, the first stage 30 and the second stages 31, 32. As shown inFIG. 12, the solder bump forming device of this embodiment includesthree discharge heads 3 a to 3 c. The actual solder bump forming devicealso includes three discharge head units 1. However, the illustration ofthese discharge head units 1 is omitted in FIG. 12. The illustration ofthe mask 8 is also omitted. In this embodiment, by focusing on adifference in moving mode of the discharge heads 3 a to 3 c, thedischarge head 3 a is also referred to as “first discharge head 3 a”,and the discharge heads 3 b, 3 c are also referred to as “seconddischarge heads 3 b, 3 c”. The solder bump forming device also includesa first stage 30 for supporting the workpiece 7, and second stages 31,32 disposed outside the first stage 30.

In this embodiment, the first stage 30 has a circular shape slightlylarger than the workpiece 7 having a circular shape. However, the firststage 30 may have any shape corresponding to the shape of the workpiece7. The second stages 31, 32 are disposed so as to opposedly face bothends of the first stage 30 in the radial direction such that the secondstages 31, 32 are in contact with an outer edge of the first stage 30.In this embodiment, the second stages 31, 32 have a rectangular shape.However, the second stages 31, 32 may have any shape which extends tothe outer edge of the first stage 30. For example, the second stages 31,32 may have a recessed shape having an arc which conforms to an arcshape of the outer edge of the first stage 30.

FIG. 13 is a cross-sectional view showing the arrangement of the firststage 30 and the second stages 31, 32. As shown in FIG. 13, the firststage 30 has a recessed portion for disposing the workpiece 7 at thecenter of the first stage 30. The recessed portion is formed to have asize at which an upper end of the recessed portion and an upper end ofthe mask 8 are flush with each other when the workpiece 7 and the mask 8are disposed in the recessed portion. Further, upper ends of the secondstage 31 and 32 are disposed at the same height as the upper end of therecessed portion of the first stage 30 and the upper end of the mask 8.With such a configuration, the first discharge head 3 a described latercan slidingly move in the horizontal direction while being in contactwith upper surfaces of the stages 30 to 32 and the mask 8.

The first discharge head 3 a is configured to move in the horizontaldirection above the workpiece 7. To be more specific, the firstdischarge head 3 a moves in a straight line while passing through thecenter of the workpiece 7 from an initial position disposed outside thefirst stage 30 (a position on the second stage 31) to a final positiondisposed outside the first stage 30 (a position on the second stage 32).

The second discharge heads 3 b, 3 c are respectively disposed on bothsides of the first discharge head 3 a. The second discharge heads 3 b, 3c move above the workpiece 7 in the same traveling direction as thefirst discharge head 3 a while changing arrangement angles of the seconddischarge heads 3 b, 3 c.

All of widths of the discharge heads 3 a to 3 c in the longitudinaldirection (in other words, a range in the discharge heads 3 a to 3 cwhere the fluid 9 can be discharged) are smaller than the width of theworkpiece 7 (in other words, a region where the workpiece 7 isdisposed). With such a configuration, the discharge heads 3 a to 3 capply the fluid 9 to the whole region of the workpiece 7 in cooperationwith each other. In other words, the discharge heads 3 a to 3 crespectively apply the fluid 9 to different regions so that the fluid 9is applied to the whole region of the workpiece 7. The width of each ofthe discharge heads 3 a to 3 c may be ¼ or more and ½ or less of thewidth of the region where the workpiece 7 is disposed. With such aconfiguration, the fluid 9 can be uniformly applied without making theconfiguration of the device excessively complicated.

FIGS. 14 to 16 show specific examples of movement paths of the dischargeheads 3 a to 3 c. FIG. 14 shows the initial position of the dischargeheads 3 a to 3 c before scanning is performed. The first discharge head3 a is disposed on the second stage 31 (not shown in FIG. 14). Thelongitudinal direction of the first discharge head 3 a is perpendicularto the traveling direction of the first discharge head 3 a (thedirection toward the upper side of the paper). The second dischargeheads 3 b, 3 c are disposed so as to be in contact with an innerperiphery of the workpiece 7 having a circular shape. In other words,the second discharge heads 3 b, 3 c are disposed forward of the firstdischarge head 3 a in the traveling direction. The longitudinaldirections of the second discharge heads 3 b, 3 c are inclined withrespect to the traveling direction of the discharge heads 3 a to 3 c(the direction toward the upper side of the paper). Such an inclinationmay be set to an angle of 10 to 60 degrees with respect to the travelingdirection, for example. The second discharge head 3 b turnscounterclockwise as the second discharge head 3 b travels in thetraveling direction. The second discharge head 3 c turns clockwise asthe second discharge head 3 c travels in the traveling direction. Theoperation where the second discharge heads 3 b, 3 c travel in thetraveling direction while turning can be realized by a robot arm, forexample.

FIG. 15 shows the discharge heads 3 a to 3 c at the intermediateposition during scanning. The first discharge head 3 a moves in astraight line from the initial position shown in FIG. 14 to the centerof the workpiece 7. A reference point RPa of the first discharge head 3a moves along a straight line L1. The second discharge heads 3 b, 3 ctravel in the traveling direction from the initial position shown inFIG. 14 while turning so that the second discharge heads 3 b, 3 c aredisposed at the same arrangement angle as the first discharge head 3 a.That is, the longitudinal direction of the first discharge head 3 a isparallel to the longitudinal directions of the second discharge heads 3b, 3 c. In this turning movement, reference points RPb, RPc of thesecond discharge heads 3 b, 3 c respectively move along the straightlines L1, L2. The reference points RPb, RPc are set at end portions ofthe discharge nozzles 5 on the first discharge head 3 a side.

FIG. 16 shows a final position of the discharge heads 3 a to 3 c afterthe scanning is finished. The first discharge head 3 a moves from theintermediate position shown in FIG. 15 to the position on the secondstage 32 (not shown in FIG. 16). The second discharge heads 3 b, 3 ctravel in the traveling direction from the intermediate position shownin FIG. 15 while turning so that the second discharge heads 3 b, 3 c areinclined with respect to the traveling direction of the discharge heads3 a to 3 c (the direction toward the upper side of the paper). Thedirections of the inclinations are opposite to the directions of theinclinations at the initial position. The inclinations may be set to anangle of 10 to 60 degrees with respect to the traveling direction, forexample.

The discharge heads 3 a to 3 c move as described above so that the fluid9 can be applied to approximately the whole region of the workpiece 7.To be more specific, the application of the fluid 9 for a center regionA1 is covered by the first discharge head 3 a. The application of thefluid 9 for a left region A2 is covered by the second discharge head 3 bon the left side. The application of the fluid 9 for a right region A3is covered by the second discharge head 3 c on the right side. Byadjusting regions where the discharge nozzles 5 a to 5 c of thedischarge heads 3 a to 3 c are formed and the reference positions RP1 toRP3, it is possible to cover a region on the workpiece 7 where the fluidis to be discharged substantially without causing the overlapping.

The above-mentioned movements of the discharge heads 3 a to 3 c may besimultaneously performed in synchronism with each other. By performingthe operation in such a manner, a processing time for the workpiece 7can be shortened. However, after the movement of at least one of thedischarge heads 3 a to 3 c is finished, the movement of the remaining ofthe discharge heads 3 a to 3 c may be started.

According to the above-mentioned solder bump forming device, the fluid 9is discharged using the plurality of discharge heads 3 a to 3 c having asmaller size than the workpiece 7. Accordingly, even when a workpiece 7has a large size, a pressure to be applied to the workpiece 7 from therespective discharge heads 3 a to 3 c is approximately uniformlydistributed. Therefore, the amount of discharge of fluid 9 can be madeuniform. Further, the second stages 31, 32 are disposed on the movementpath of the first discharge head 3 a at positions outside the firststage 30 and hence, the first discharge head 3 a can apply the fluidfrom an outer edge to another outer edge of the workpiece 7. Further,the second discharge heads 3 b, 3 c move while changing arrangementangles thereof and hence, even when the application is started from aposition above the workpiece 7, the fluid 9 can be discharged in a widerange. Accordingly, the fluid 9 can be discharged over a wide rangeregion of the workpiece 7. Particularly, as in the case of thisembodiment, with the use of one first discharge head 3 a and two seconddischarge heads 3 b, 3 c, the fluid can be efficiently applied toapproximately the whole region of the workpiece 7 having a circularshape. However, the number of discharge heads 3 may be set to any numberof 2 or more according to the size or the shape of the workpiece 7.

REFERENCE SIGNS LIST

1: discharge head unit

2: fluid tank

3, 3 a, 3 b, 3 c: discharge head

4: heater

5: discharge nozzle

6: suction port

7: workpiece

8: mask

9: fluid

10: extension pipeline

11: pressure supply means

12: suction pipe extension pipeline

13: reduced pressure supply means

14: pressure generating source

16: micro ejector

18: throttle valve

19: pressure generating source

22: fluid supply device

30: first stage

31, 32: second stage

What is claimed is:
 1. A method for discharging fluid for applying thefluid into a mask on a circular workpiece of electronic component, themethod comprising using a fluid discharge device including a head unit,the head unit including a tank capable of storing the fluid and providedwith a first heater, and a discharge head, to discharge the fluid from adischarge nozzle by reciprocating the discharge head with respect to theworkpiece, after sucking air or the fluid in the mask from a suctionport, wherein the head unit has a longitudinal width shorter than adiameter of the workpiece, the discharge head has the suction port forsucking a substance in the mask on the workpiece formed on a forwardside of a traveling direction of the discharge head, and the dischargenozzle for discharging the fluid formed on a backward side of thetraveling direction, and a second heater is provided at a lower end ofthe discharge nozzle.
 2. The method for discharging the fluid accordingto claim 1, wherein the discharge head has opening portions having aslit shape as a shape of the discharge nozzle and the suction port. 3.The method for discharging the fluid according to claim 1, wherein thesuction port is disposed on both sides of the discharge nozzle in thedischarge head.